Author Topic: LARGE oil leak (Read 4437 times)

KenC · « **on:** June 02, 2011, 11:59:19 AM »

My car recently developed a large oil leak. Looks like it's coming from the junction where the head, block and timing case come together.

Is there any harm in giving that headbolt there another 90-180deg turn?

monty23psk · « **Reply #1 on:** June 02, 2011, 12:56:44 PM »

Overtighten can break the bolt. How much giving it another turn would be, not sure. You also don't want to warp the head and then get more of a leak. I have broken one of these headbolts by overtighting, torque wrench was off the calibration big time.

KenC · « **Reply #2 on:** June 02, 2011, 01:07:33 PM »

Quote from: monty23psk;104307

Overtighten can break the bolt. How much giving it another turn would be, not sure. You also don't want to warp the head and then get more of a leak. I have broken one of these headbolts by overtighting, torque wrench was off the calibration big time.

Breaking it is what I'm worried about. I'm not comfortable giving it more than a half turn. I'd probably just turn it another 90 and watch the leak.

Would it be less likely to break when it's hot or cold?

It's been about 10k since the head was put on.

monty23psk · « **Reply #3 on:** June 02, 2011, 01:38:50 PM »

Metal gets softer with heat so I would say hot, but then it eaiser to warp. So not idea which will better. Another 90 should make to much of a difference. How many bolts, just 1?

KenC · « **Reply #4 on:** June 02, 2011, 02:04:00 PM »

Yeah, there's just one head bolt by the oil passage there. It's the front passenger one.

bmwman91 · « **Reply #5 on:** June 02, 2011, 08:47:54 PM »

It may be the profile gasket leaking. Tightening a head bolt wouldn't help with that. Either that, or maybe the valve cover gasket is crapped out & oil is running down the side. That is really common.

KenC · « **Reply #6 on:** June 03, 2011, 08:50:13 AM »

Quote from: bmwman91;104324

It may be the profile gasket leaking. Tightening a head bolt wouldn't help with that. Either that, or maybe the valve cover gasket is crapped out & oil is running down the side. That is really common.

Definitely not the valve cover gasket. I could be the profile gasket.

I put the head on ~10k ago. I tightened all of the headbolts down to spec and haven't touched it since. Some have mentioned that I should have retorqued them, but I thought it was unnecessary with the stretch bolts. Is it possible a head bolt has loosened up? What's the final torque spec on the head bolts after the two 90deg turns?

DesktopDave · « **Reply #7 on:** June 03, 2011, 10:26:42 AM »

I'd suggest re-tightening them all to spec too. Pressurized oil likes to find the weak spots on gaskets. Might be a loose bolt...I'd do it just for peace of mind. I thought BMW recommended rechecking the bolts after so many miles? I'm not sure though.

It's a risk, no doubt, but I'd suspect that the bolts will take it. If you're risk-averse, just replace it with a new bolt & torque to spec.

monty23psk · « **Reply #8 on:** June 03, 2011, 10:30:12 AM »

What you can do is set your torque wrench to the correct spec (30nm?) and try if it clicks, then it is torqued, but not sure about the 2 90-degree turns. You can raise the number to have an idea when you start to turn it with out clicking. Also you can then spot check a few bolts are all to make sure they are all the same.

KenC · « **Reply #9 on:** June 03, 2011, 10:47:39 AM »

Torque process is 22lb/ft, then 90deg, then another 90deg. Without knowing what the final torque spec is, there's not really a way to test it.

Can I buy just one headbolt?

monty23psk · « **Reply #10 on:** June 03, 2011, 12:44:50 PM »

No, the headbolts come in sets, I did have 9 new ones as I installed a few and wrench broke and the over torqued it and broke one. I would have to check to see if I still have them but dont think so. If you know you torqued it correctly, you can work backwards to figure out the torque. Just start at 91 and it should click, keep increasing until it is able to start turning without clicking. Have a test block, head and bolt would be ideal. I am sure there is some match equation to figure out what a quarter turn of a certain metal and bolt size will give you but that is beyond the scope of my knowledge.

woof132 · « **Reply #11 on:** June 07, 2011, 11:07:39 AM »

do not retorque or even just tighten a head bolt! you could very easily end up warping the head or possibly breaking the head gasket. that, and the head gaskets are not prone to leaking oil. there are lots of potential leaking gaskets in the area you have described. I would remove the upper timing case cover first. the gasket between the upper and lower timing case covers is very prone to leaking, and when it does leak, it doesn't hold back. I would order a new gasket and use an excellent silicone gasket compound on it. then retorque all timing case cover bolts to the proper spec, and ensure that the gasket hasn't been pinched anywhere as it is easy to do with that gasket. my recommendation for gasket compound is toyota's. you can get it at a toyota dealership. just ask for their gasket compound. the stuff is the best. if the profile gasket were leaking, you would have water mixing in with your oil. check the dipstick and oil filler cap for a mayonnaise-type goop. that would indicate water mixing with oil.

bmwman91 · « **Reply #12 on:** June 07, 2011, 11:24:59 AM »

I'm with Woof. All of the paper gaskets on the motor weep oil if they are installed without some sort of sealer, and it is more severe if you run synthetic oil.

Personally, I prefer to use non-curing high-temp gasket sealing compounds. Some folks recommend one by Permatex with "Hylomar" additive or something. I couldn't find it anywhere, so I used their regular stuff that resists oil, coolant, PS fluid and can operate continuously at 450F.

If it turns out that it IS the head gasket, you have bigger issues than the oil leak anyway. You would definitely want to pull the head & have it decked. What all was done with it when you had it off ~10k miles ago?